A commando unit from the US Navy’s Seal Team Six launched an amphibious raid on a Somali town, but failed to confirm a capture or kill of their Al Shabab target, suspected to be linked to Nairobi’s Westgate mall terror attack.

The operation could have opposite its intended result of discouraging further attacks. Analysts warn that even earlier successful targeted strikes against Al Shabab, a Somalia-based Islamist militant group, failed to curb the group's capacity to carry out international terror attacks, and that failed missions could in fact bolster its support and recruitment.

The predawn raid Saturday came unstuck when the US troops were faced with heavier-than-expected return fire, and pulled out to avoid civilian casualties, two security sources said. No Americans were injured.